At the conclusion of erythropoiesis, erythroblasts expel their nuclei to become reticulocytes. In this process, partitioning of plasma membrane components between the extruded nucleus and young reticulocyte is governed by the molecular organization of the membrane and skeletal network. The differences in morphology and mechanical properties of reticulocytes and erythrocytes suggest alterations of membrane organization during reticulocyte maturation. Such organizational changes may also cause the loss of function of adhesion molecules, such as Lu, LW and CD47, in erythrocytes. Little is known regarding the molecular organization of the young reticulocyte membrane and skeletal network. This proposal is designed to apply various techniques, including protein electrophoresis, Western blot analysis. immunotluorescence microscopy, cell culture, and single cell micropipette manipulation, to investigate the molecular organization and dynamics of membrane and skeletal molecules in the young reticulocyte and the effect of specific liganding on membrane organization and mechanical properties of the skeletal network.